Graduate students Cristian Crisan and Aroon Chande discover a novel, active toxin used by the pathogenic bacterium Vibrio cholerae to kill competitor cells.

Microbes live inside crowded communities in the environment and in hosts. Many wield a toxin-tipped harpoon called the Type 6 Secretion System (T6SS) to poke and kill competitors. The pathogenic bacterium Vibrio cholerae uses its T6SS weapon to survive in water and cause massive outbreaks of fatal cholera. In places like Yemen and Haiti, where water supplies are often contaminated and proper sanitation techniques are unavailable, cholera epidemics cause thousands of deaths. Only a few V. cholerae T6SS toxins have been described in prior studies that focused on outbreak strains, but the Hammer lab suspected novel toxins might be discovered by examining less-studied samples from environmental sources. In a collaborative study published in Genome Biology with Georgia Tech colleagues from the Jordan and Yunker labs, graduate students Cristian Crisan and Aroon Chande develop a computational tool, find several new T6SS toxins, and show that one of them is highly efficient at killing competitors. Currently, Cristian is studying the molecular mechanism by which another of the toxins can kill other cells.